SUMMARY Urinary glycosaminoglycan (GAG) excretion was measured in 24 patients with active rheumatoid arthritis (RA) before and after treatment with conventional second-line agents. Urinary GAG excretion was also measured in normal controls, patients with osteoarthritis (OA), and patients with acute myocardial infarction (MI). Total GAG excretion was increased in the RA group and fell after second-line therapy (p<001). More low than high molecular weight GAG was excreted in the active RA group, and this pattern was reversed after treatment. Excretion of total, high and low molecular weight GAG in the OA group did not differ significantly from controls. Total GAG excretion was increased in the MI group when compared with controls (p<002) and consisted mainly of high molecular weight GAG. The serial measurement of urinary GAG provides a further index of disease activity and may help to monitor response to treatment.Key words: serial measurements, alcian blue, disease activity.Previous workers have shown that urinarv excretion of sulphated glycosaminoglycans (GAG) is increased in connective tissue disorders such as progressive systemic sclerosis' and rheumatoid arthritis (RA).2The amount of high molecular weight GAG and low molecular weight GAG excreted varies in different disorders and with disease activity.3 4 To establish whether measurement of urinary GAG excretion and the relative amounts of high and low molecular weight GAG provide a useful additional index of inflammatory disease activity, patients with RA were studied before and after commencing second-line drug therapy with chloroquine, gold, or D-penicillamine. The results of GAG excretion in RA were compared with GAG excretion in patients with osteoarthritis (OA), in patients after acute myocardial infarction (MI), and in normal controls. The OA and MI groups were chosen to study the effects of non-inflammatory joint disease and acute nonarticular tissue damage respectively on GAG excretion.
